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What would happen to a modern skyscraper if it rains micro blackholes?


What would happen if the black hole at the center of a galaxy was removed?What would happen if magnets stopped working?What would getting hit by a micro black hole laser look like?What would kill all flora on Earth and what would happen with the atmosphereWhat would happen to Earth if Yellowstone EruptedWhat exactly would happen if a black hole was introduced into the sun?What would happen to landfills if abandoned for many years?What would happen to a planet after a quarter of it had been blown up?What would happen if you could remove the event horizon from Sgr A*?What would cause an entire space-faring civilization to “expire”













4












$begingroup$


Set in present day New York City, an unknown spacecraft of alien origin expelled millions of micro blackholes each with the mass of a grape in the earth atmosphere. I like to know what happens if these millions of micro blackholes were to fall on building structures such as skyscrapers, would it trigger an extinction level event?










share|improve this question











$endgroup$







  • 3




    $begingroup$
    Given the aliens could easily send waves of asteroids to destroy Earth's surface completely with practically trivial effort (at their tech level), mucking around with micro black holes (or any black holes) seems quite daft.
    $endgroup$
    – StephenG
    16 hours ago










  • $begingroup$
    How about they expell at fraction of c so we take length contraction into question?
    $endgroup$
    – user6760
    16 hours ago






  • 1




    $begingroup$
    @user6760 what do you want to happen or expect to happen? I presume you chose black holes for a reason.
    $endgroup$
    – Snyder005
    10 hours ago










  • $begingroup$
    @StephenG - an entire can of micro black holes fits in the storage cupboard in the corner of the spacecraft's kitchen (which has a stasis field to keep food fresh, and keep black holes from evaporating), going out and dragging waves of asteroids is a lot more work than just opening a can of micro-blackholes and sprinkling them out a hatch.
    $endgroup$
    – Johnny
    6 hours ago











  • $begingroup$
    @Johnny As explained in answers, in an instant of time after you open the "can" (remove the magic statsis field) so short you could not measure it, all the micro black holes evaporate (with a huge out-pouring of radiation like a nuke). Dragging asteroids is what we in engineering call "safer", at least for the aliens - but still kills the pesky humans. :-)
    $endgroup$
    – StephenG
    4 hours ago















4












$begingroup$


Set in present day New York City, an unknown spacecraft of alien origin expelled millions of micro blackholes each with the mass of a grape in the earth atmosphere. I like to know what happens if these millions of micro blackholes were to fall on building structures such as skyscrapers, would it trigger an extinction level event?










share|improve this question











$endgroup$







  • 3




    $begingroup$
    Given the aliens could easily send waves of asteroids to destroy Earth's surface completely with practically trivial effort (at their tech level), mucking around with micro black holes (or any black holes) seems quite daft.
    $endgroup$
    – StephenG
    16 hours ago










  • $begingroup$
    How about they expell at fraction of c so we take length contraction into question?
    $endgroup$
    – user6760
    16 hours ago






  • 1




    $begingroup$
    @user6760 what do you want to happen or expect to happen? I presume you chose black holes for a reason.
    $endgroup$
    – Snyder005
    10 hours ago










  • $begingroup$
    @StephenG - an entire can of micro black holes fits in the storage cupboard in the corner of the spacecraft's kitchen (which has a stasis field to keep food fresh, and keep black holes from evaporating), going out and dragging waves of asteroids is a lot more work than just opening a can of micro-blackholes and sprinkling them out a hatch.
    $endgroup$
    – Johnny
    6 hours ago











  • $begingroup$
    @Johnny As explained in answers, in an instant of time after you open the "can" (remove the magic statsis field) so short you could not measure it, all the micro black holes evaporate (with a huge out-pouring of radiation like a nuke). Dragging asteroids is what we in engineering call "safer", at least for the aliens - but still kills the pesky humans. :-)
    $endgroup$
    – StephenG
    4 hours ago













4












4








4





$begingroup$


Set in present day New York City, an unknown spacecraft of alien origin expelled millions of micro blackholes each with the mass of a grape in the earth atmosphere. I like to know what happens if these millions of micro blackholes were to fall on building structures such as skyscrapers, would it trigger an extinction level event?










share|improve this question











$endgroup$




Set in present day New York City, an unknown spacecraft of alien origin expelled millions of micro blackholes each with the mass of a grape in the earth atmosphere. I like to know what happens if these millions of micro blackholes were to fall on building structures such as skyscrapers, would it trigger an extinction level event?







apocalypse weapon-mass-destruction black-holes extinction






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 15 hours ago









Renan

52.6k15120261




52.6k15120261










asked 16 hours ago









user6760user6760

13.6k1676166




13.6k1676166







  • 3




    $begingroup$
    Given the aliens could easily send waves of asteroids to destroy Earth's surface completely with practically trivial effort (at their tech level), mucking around with micro black holes (or any black holes) seems quite daft.
    $endgroup$
    – StephenG
    16 hours ago










  • $begingroup$
    How about they expell at fraction of c so we take length contraction into question?
    $endgroup$
    – user6760
    16 hours ago






  • 1




    $begingroup$
    @user6760 what do you want to happen or expect to happen? I presume you chose black holes for a reason.
    $endgroup$
    – Snyder005
    10 hours ago










  • $begingroup$
    @StephenG - an entire can of micro black holes fits in the storage cupboard in the corner of the spacecraft's kitchen (which has a stasis field to keep food fresh, and keep black holes from evaporating), going out and dragging waves of asteroids is a lot more work than just opening a can of micro-blackholes and sprinkling them out a hatch.
    $endgroup$
    – Johnny
    6 hours ago











  • $begingroup$
    @Johnny As explained in answers, in an instant of time after you open the "can" (remove the magic statsis field) so short you could not measure it, all the micro black holes evaporate (with a huge out-pouring of radiation like a nuke). Dragging asteroids is what we in engineering call "safer", at least for the aliens - but still kills the pesky humans. :-)
    $endgroup$
    – StephenG
    4 hours ago












  • 3




    $begingroup$
    Given the aliens could easily send waves of asteroids to destroy Earth's surface completely with practically trivial effort (at their tech level), mucking around with micro black holes (or any black holes) seems quite daft.
    $endgroup$
    – StephenG
    16 hours ago










  • $begingroup$
    How about they expell at fraction of c so we take length contraction into question?
    $endgroup$
    – user6760
    16 hours ago






  • 1




    $begingroup$
    @user6760 what do you want to happen or expect to happen? I presume you chose black holes for a reason.
    $endgroup$
    – Snyder005
    10 hours ago










  • $begingroup$
    @StephenG - an entire can of micro black holes fits in the storage cupboard in the corner of the spacecraft's kitchen (which has a stasis field to keep food fresh, and keep black holes from evaporating), going out and dragging waves of asteroids is a lot more work than just opening a can of micro-blackholes and sprinkling them out a hatch.
    $endgroup$
    – Johnny
    6 hours ago











  • $begingroup$
    @Johnny As explained in answers, in an instant of time after you open the "can" (remove the magic statsis field) so short you could not measure it, all the micro black holes evaporate (with a huge out-pouring of radiation like a nuke). Dragging asteroids is what we in engineering call "safer", at least for the aliens - but still kills the pesky humans. :-)
    $endgroup$
    – StephenG
    4 hours ago







3




3




$begingroup$
Given the aliens could easily send waves of asteroids to destroy Earth's surface completely with practically trivial effort (at their tech level), mucking around with micro black holes (or any black holes) seems quite daft.
$endgroup$
– StephenG
16 hours ago




$begingroup$
Given the aliens could easily send waves of asteroids to destroy Earth's surface completely with practically trivial effort (at their tech level), mucking around with micro black holes (or any black holes) seems quite daft.
$endgroup$
– StephenG
16 hours ago












$begingroup$
How about they expell at fraction of c so we take length contraction into question?
$endgroup$
– user6760
16 hours ago




$begingroup$
How about they expell at fraction of c so we take length contraction into question?
$endgroup$
– user6760
16 hours ago




1




1




$begingroup$
@user6760 what do you want to happen or expect to happen? I presume you chose black holes for a reason.
$endgroup$
– Snyder005
10 hours ago




$begingroup$
@user6760 what do you want to happen or expect to happen? I presume you chose black holes for a reason.
$endgroup$
– Snyder005
10 hours ago












$begingroup$
@StephenG - an entire can of micro black holes fits in the storage cupboard in the corner of the spacecraft's kitchen (which has a stasis field to keep food fresh, and keep black holes from evaporating), going out and dragging waves of asteroids is a lot more work than just opening a can of micro-blackholes and sprinkling them out a hatch.
$endgroup$
– Johnny
6 hours ago





$begingroup$
@StephenG - an entire can of micro black holes fits in the storage cupboard in the corner of the spacecraft's kitchen (which has a stasis field to keep food fresh, and keep black holes from evaporating), going out and dragging waves of asteroids is a lot more work than just opening a can of micro-blackholes and sprinkling them out a hatch.
$endgroup$
– Johnny
6 hours ago













$begingroup$
@Johnny As explained in answers, in an instant of time after you open the "can" (remove the magic statsis field) so short you could not measure it, all the micro black holes evaporate (with a huge out-pouring of radiation like a nuke). Dragging asteroids is what we in engineering call "safer", at least for the aliens - but still kills the pesky humans. :-)
$endgroup$
– StephenG
4 hours ago




$begingroup$
@Johnny As explained in answers, in an instant of time after you open the "can" (remove the magic statsis field) so short you could not measure it, all the micro black holes evaporate (with a huge out-pouring of radiation like a nuke). Dragging asteroids is what we in engineering call "safer", at least for the aliens - but still kills the pesky humans. :-)
$endgroup$
– StephenG
4 hours ago










4 Answers
4






active

oldest

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20












$begingroup$


would it triggers extinction level event?




Since they'd evaporate more or less instantaneously (known as Hawking radiation), releasing energy according to the famous equation beginning E=, the spaceship would last a few microseconds at best, Earth would be fine.



Yes, the aliens in the ship would become extinct.






share|improve this answer









$endgroup$








  • 5




    $begingroup$
    According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
    $endgroup$
    – Tyler S. Loeper
    16 hours ago







  • 2




    $begingroup$
    @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
    $endgroup$
    – Agrajag
    16 hours ago







  • 2




    $begingroup$
    How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
    $endgroup$
    – John Dvorak
    15 hours ago







  • 2




    $begingroup$
    @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
    $endgroup$
    – Alexander
    9 hours ago










  • $begingroup$
    @Alexander well, that counts as success in my book! :P
    $endgroup$
    – John Dvorak
    9 hours ago


















15












$begingroup$

Black holes evaporate by emitting Hawking radiation




a 1-second-life black hole has a mass of $2.28 cdot 10^5 kg$




A grape has far less mass than that, thus the black hole would evaporate way faster than that.



An intelligent life form dropping micro black holes on Earth would thus quickly annihilate its own bombing squad in a shower of gamma ray, proving that they were not so intelligent as we thought.






share|improve this answer









$endgroup$












  • $begingroup$
    So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
    $endgroup$
    – reirab
    8 hours ago










  • $begingroup$
    @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
    $endgroup$
    – Gryphon
    4 hours ago


















9












$begingroup$

The electromagnetic force from one electron on another and the gravitational force of this micro-black hole both follow an inverse square law. A grape about 1.5 cm in radius would have a mass of about 0.015 kg.



When does the gravitational force of the grape exceed the electromagnetic force between electrons ? It's when :



$$frac r R < sqrtfrac 4pi epsilon_0Gm_em_he^2 = 6.3times 10^-8$$



Meaning the black hole would have to pass less than one ten millionth of the distance between electrons to have a significant influence on one. Away from than range the electron will happily go about it's business hardly disturbed at all.



Even if a black hole passes this close the effect is only temporary. You're still nowhere near the event horizon of that black hole and so the electron will, at worst, be pulled away from it's normal motion and after some brief period when the black hole moves away it will simply recombined in some way with the bulk of atoms around it. It might cause a minute amount of damage on a molecular level (even allowing for millions of these micro black holes), but the net effect would be tiny, probably less that someone hitting a wall with their hand.




How about they expell at fraction of c so we take length contraction into question?




You seem to mean that to avoid Hawking radiation evaporation destroying these black holes before they even reach the black hole, they could be ejected at a high fraction of the speed of light.



So how high a speed is needed to avoid them evaporating before they travel 100 meters, assuming your aliens like low level flying ?



The fraction of the speed of light needed is :



$$frac v c > frac 1 sqrt 1 + left( frac Tc L right)^2 $$



Where $L$ is the distance they must travel and $T$ is the lifetime of the micro black hole before it evaporates.



This works out at $frac v c approx 1 - 2times 10^-19$. That's insanely close to the speed of light.



A million grapes of mass 0.015 kg will have a mass of 15,000 kg. But the energy required to get them moving at this insane fraction of the speed of light would be enormous. It equates to a mass about $2times 10^9$ times 15,000 kg. Or to put it another way, the ship firing these micro black holes would need to have a mass-energy of about $3times 10^13$ kg. The asteroid Vesta is substantially larger than this.



So this is actually a small mass in terms of asteroids and you could probably destroy Earth a lot more easily simply by grabbing some handy largish asteroids and sending them on their merry way towards Earth at some modest speed that's easily imparted with your spaceship.



Conclusion :



No need at all to mess around with ultra-relativistic micro-black holes when the universe provides you with much simpler and easy to handle "ammunition" in the form of basic asteroids.






share|improve this answer









$endgroup$












  • $begingroup$
    I was wondering about that speed, thanks for working it out.
    $endgroup$
    – Kevin
    9 hours ago










  • $begingroup$
    Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
    $endgroup$
    – Mark
    7 hours ago










  • $begingroup$
    Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
    $endgroup$
    – Gryphon
    4 hours ago










  • $begingroup$
    👍for addressing my comment too
    $endgroup$
    – user6760
    3 hours ago


















0












$begingroup$

If we take "size of a grape" to mean a gram, then a million of them would be 1 metric ton. When they evaporate, they release energy on the order of magnitude of a nuclear bomb. So New York would be devastated, but the earth as whole would not have large effects, although it might produce radioactive elements that would increase cancer rates.






share|improve this answer









$endgroup$













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    4 Answers
    4






    active

    oldest

    votes








    4 Answers
    4






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    20












    $begingroup$


    would it triggers extinction level event?




    Since they'd evaporate more or less instantaneously (known as Hawking radiation), releasing energy according to the famous equation beginning E=, the spaceship would last a few microseconds at best, Earth would be fine.



    Yes, the aliens in the ship would become extinct.






    share|improve this answer









    $endgroup$








    • 5




      $begingroup$
      According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
      $endgroup$
      – Tyler S. Loeper
      16 hours ago







    • 2




      $begingroup$
      @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
      $endgroup$
      – Agrajag
      16 hours ago







    • 2




      $begingroup$
      How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
      $endgroup$
      – John Dvorak
      15 hours ago







    • 2




      $begingroup$
      @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
      $endgroup$
      – Alexander
      9 hours ago










    • $begingroup$
      @Alexander well, that counts as success in my book! :P
      $endgroup$
      – John Dvorak
      9 hours ago















    20












    $begingroup$


    would it triggers extinction level event?




    Since they'd evaporate more or less instantaneously (known as Hawking radiation), releasing energy according to the famous equation beginning E=, the spaceship would last a few microseconds at best, Earth would be fine.



    Yes, the aliens in the ship would become extinct.






    share|improve this answer









    $endgroup$








    • 5




      $begingroup$
      According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
      $endgroup$
      – Tyler S. Loeper
      16 hours ago







    • 2




      $begingroup$
      @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
      $endgroup$
      – Agrajag
      16 hours ago







    • 2




      $begingroup$
      How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
      $endgroup$
      – John Dvorak
      15 hours ago







    • 2




      $begingroup$
      @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
      $endgroup$
      – Alexander
      9 hours ago










    • $begingroup$
      @Alexander well, that counts as success in my book! :P
      $endgroup$
      – John Dvorak
      9 hours ago













    20












    20








    20





    $begingroup$


    would it triggers extinction level event?




    Since they'd evaporate more or less instantaneously (known as Hawking radiation), releasing energy according to the famous equation beginning E=, the spaceship would last a few microseconds at best, Earth would be fine.



    Yes, the aliens in the ship would become extinct.






    share|improve this answer









    $endgroup$




    would it triggers extinction level event?




    Since they'd evaporate more or less instantaneously (known as Hawking radiation), releasing energy according to the famous equation beginning E=, the spaceship would last a few microseconds at best, Earth would be fine.



    Yes, the aliens in the ship would become extinct.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 16 hours ago









    AgrajagAgrajag

    6,94911350




    6,94911350







    • 5




      $begingroup$
      According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
      $endgroup$
      – Tyler S. Loeper
      16 hours ago







    • 2




      $begingroup$
      @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
      $endgroup$
      – Agrajag
      16 hours ago







    • 2




      $begingroup$
      How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
      $endgroup$
      – John Dvorak
      15 hours ago







    • 2




      $begingroup$
      @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
      $endgroup$
      – Alexander
      9 hours ago










    • $begingroup$
      @Alexander well, that counts as success in my book! :P
      $endgroup$
      – John Dvorak
      9 hours ago












    • 5




      $begingroup$
      According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
      $endgroup$
      – Tyler S. Loeper
      16 hours ago







    • 2




      $begingroup$
      @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
      $endgroup$
      – Agrajag
      16 hours ago







    • 2




      $begingroup$
      How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
      $endgroup$
      – John Dvorak
      15 hours ago







    • 2




      $begingroup$
      @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
      $endgroup$
      – Alexander
      9 hours ago










    • $begingroup$
      @Alexander well, that counts as success in my book! :P
      $endgroup$
      – John Dvorak
      9 hours ago







    5




    5




    $begingroup$
    According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
    $endgroup$
    – Tyler S. Loeper
    16 hours ago





    $begingroup$
    According to this calculator (eguruchela.com/physics/calculator/…), they would last 1.6581375e-29 seconds. There is also the fact that their radius would be so small, that they wouldn't even interact with atoms most of the time.
    $endgroup$
    – Tyler S. Loeper
    16 hours ago





    2




    2




    $begingroup$
    @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
    $endgroup$
    – Agrajag
    16 hours ago





    $begingroup$
    @TylerS.Loeper Gosh, we don't have an SI multiplier to express that, atto is feeling left out and lonely.
    $endgroup$
    – Agrajag
    16 hours ago





    2




    2




    $begingroup$
    How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
    $endgroup$
    – John Dvorak
    15 hours ago





    $begingroup$
    How about they just pick the right size black holes that they evaporate with a boom after they reach Earth? That shouldn't be too hard. They'd only be grape sized for a tiny while, but that's fine.
    $endgroup$
    – John Dvorak
    15 hours ago





    2




    2




    $begingroup$
    @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
    $endgroup$
    – Alexander
    9 hours ago




    $begingroup$
    @John Dvorak a 1,000 metric tons black hole will have a lifespan of 84 seconds. It may be enough to reach the surface, but it's going to release an energy amount equivalent to teratons of TNT.
    $endgroup$
    – Alexander
    9 hours ago












    $begingroup$
    @Alexander well, that counts as success in my book! :P
    $endgroup$
    – John Dvorak
    9 hours ago




    $begingroup$
    @Alexander well, that counts as success in my book! :P
    $endgroup$
    – John Dvorak
    9 hours ago











    15












    $begingroup$

    Black holes evaporate by emitting Hawking radiation




    a 1-second-life black hole has a mass of $2.28 cdot 10^5 kg$




    A grape has far less mass than that, thus the black hole would evaporate way faster than that.



    An intelligent life form dropping micro black holes on Earth would thus quickly annihilate its own bombing squad in a shower of gamma ray, proving that they were not so intelligent as we thought.






    share|improve this answer









    $endgroup$












    • $begingroup$
      So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
      $endgroup$
      – reirab
      8 hours ago










    • $begingroup$
      @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
      $endgroup$
      – Gryphon
      4 hours ago















    15












    $begingroup$

    Black holes evaporate by emitting Hawking radiation




    a 1-second-life black hole has a mass of $2.28 cdot 10^5 kg$




    A grape has far less mass than that, thus the black hole would evaporate way faster than that.



    An intelligent life form dropping micro black holes on Earth would thus quickly annihilate its own bombing squad in a shower of gamma ray, proving that they were not so intelligent as we thought.






    share|improve this answer









    $endgroup$












    • $begingroup$
      So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
      $endgroup$
      – reirab
      8 hours ago










    • $begingroup$
      @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
      $endgroup$
      – Gryphon
      4 hours ago













    15












    15








    15





    $begingroup$

    Black holes evaporate by emitting Hawking radiation




    a 1-second-life black hole has a mass of $2.28 cdot 10^5 kg$




    A grape has far less mass than that, thus the black hole would evaporate way faster than that.



    An intelligent life form dropping micro black holes on Earth would thus quickly annihilate its own bombing squad in a shower of gamma ray, proving that they were not so intelligent as we thought.






    share|improve this answer









    $endgroup$



    Black holes evaporate by emitting Hawking radiation




    a 1-second-life black hole has a mass of $2.28 cdot 10^5 kg$




    A grape has far less mass than that, thus the black hole would evaporate way faster than that.



    An intelligent life form dropping micro black holes on Earth would thus quickly annihilate its own bombing squad in a shower of gamma ray, proving that they were not so intelligent as we thought.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 16 hours ago









    L.DutchL.Dutch

    90.3k29209437




    90.3k29209437











    • $begingroup$
      So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
      $endgroup$
      – reirab
      8 hours ago










    • $begingroup$
      @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
      $endgroup$
      – Gryphon
      4 hours ago
















    • $begingroup$
      So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
      $endgroup$
      – reirab
      8 hours ago










    • $begingroup$
      @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
      $endgroup$
      – Gryphon
      4 hours ago















    $begingroup$
    So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
    $endgroup$
    – reirab
    8 hours ago




    $begingroup$
    So, basically, aliens playing with tech they don't quite fully understand yet resulting in unintended consequences. Basically an alien version of the early Cold War period.
    $endgroup$
    – reirab
    8 hours ago












    $begingroup$
    @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
    $endgroup$
    – Gryphon
    4 hours ago




    $begingroup$
    @reirab, I mean, we managed not to blow ourselves up during the Cold War, so... score one for humanity I guess?
    $endgroup$
    – Gryphon
    4 hours ago











    9












    $begingroup$

    The electromagnetic force from one electron on another and the gravitational force of this micro-black hole both follow an inverse square law. A grape about 1.5 cm in radius would have a mass of about 0.015 kg.



    When does the gravitational force of the grape exceed the electromagnetic force between electrons ? It's when :



    $$frac r R < sqrtfrac 4pi epsilon_0Gm_em_he^2 = 6.3times 10^-8$$



    Meaning the black hole would have to pass less than one ten millionth of the distance between electrons to have a significant influence on one. Away from than range the electron will happily go about it's business hardly disturbed at all.



    Even if a black hole passes this close the effect is only temporary. You're still nowhere near the event horizon of that black hole and so the electron will, at worst, be pulled away from it's normal motion and after some brief period when the black hole moves away it will simply recombined in some way with the bulk of atoms around it. It might cause a minute amount of damage on a molecular level (even allowing for millions of these micro black holes), but the net effect would be tiny, probably less that someone hitting a wall with their hand.




    How about they expell at fraction of c so we take length contraction into question?




    You seem to mean that to avoid Hawking radiation evaporation destroying these black holes before they even reach the black hole, they could be ejected at a high fraction of the speed of light.



    So how high a speed is needed to avoid them evaporating before they travel 100 meters, assuming your aliens like low level flying ?



    The fraction of the speed of light needed is :



    $$frac v c > frac 1 sqrt 1 + left( frac Tc L right)^2 $$



    Where $L$ is the distance they must travel and $T$ is the lifetime of the micro black hole before it evaporates.



    This works out at $frac v c approx 1 - 2times 10^-19$. That's insanely close to the speed of light.



    A million grapes of mass 0.015 kg will have a mass of 15,000 kg. But the energy required to get them moving at this insane fraction of the speed of light would be enormous. It equates to a mass about $2times 10^9$ times 15,000 kg. Or to put it another way, the ship firing these micro black holes would need to have a mass-energy of about $3times 10^13$ kg. The asteroid Vesta is substantially larger than this.



    So this is actually a small mass in terms of asteroids and you could probably destroy Earth a lot more easily simply by grabbing some handy largish asteroids and sending them on their merry way towards Earth at some modest speed that's easily imparted with your spaceship.



    Conclusion :



    No need at all to mess around with ultra-relativistic micro-black holes when the universe provides you with much simpler and easy to handle "ammunition" in the form of basic asteroids.






    share|improve this answer









    $endgroup$












    • $begingroup$
      I was wondering about that speed, thanks for working it out.
      $endgroup$
      – Kevin
      9 hours ago










    • $begingroup$
      Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
      $endgroup$
      – Mark
      7 hours ago










    • $begingroup$
      Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
      $endgroup$
      – Gryphon
      4 hours ago










    • $begingroup$
      👍for addressing my comment too
      $endgroup$
      – user6760
      3 hours ago















    9












    $begingroup$

    The electromagnetic force from one electron on another and the gravitational force of this micro-black hole both follow an inverse square law. A grape about 1.5 cm in radius would have a mass of about 0.015 kg.



    When does the gravitational force of the grape exceed the electromagnetic force between electrons ? It's when :



    $$frac r R < sqrtfrac 4pi epsilon_0Gm_em_he^2 = 6.3times 10^-8$$



    Meaning the black hole would have to pass less than one ten millionth of the distance between electrons to have a significant influence on one. Away from than range the electron will happily go about it's business hardly disturbed at all.



    Even if a black hole passes this close the effect is only temporary. You're still nowhere near the event horizon of that black hole and so the electron will, at worst, be pulled away from it's normal motion and after some brief period when the black hole moves away it will simply recombined in some way with the bulk of atoms around it. It might cause a minute amount of damage on a molecular level (even allowing for millions of these micro black holes), but the net effect would be tiny, probably less that someone hitting a wall with their hand.




    How about they expell at fraction of c so we take length contraction into question?




    You seem to mean that to avoid Hawking radiation evaporation destroying these black holes before they even reach the black hole, they could be ejected at a high fraction of the speed of light.



    So how high a speed is needed to avoid them evaporating before they travel 100 meters, assuming your aliens like low level flying ?



    The fraction of the speed of light needed is :



    $$frac v c > frac 1 sqrt 1 + left( frac Tc L right)^2 $$



    Where $L$ is the distance they must travel and $T$ is the lifetime of the micro black hole before it evaporates.



    This works out at $frac v c approx 1 - 2times 10^-19$. That's insanely close to the speed of light.



    A million grapes of mass 0.015 kg will have a mass of 15,000 kg. But the energy required to get them moving at this insane fraction of the speed of light would be enormous. It equates to a mass about $2times 10^9$ times 15,000 kg. Or to put it another way, the ship firing these micro black holes would need to have a mass-energy of about $3times 10^13$ kg. The asteroid Vesta is substantially larger than this.



    So this is actually a small mass in terms of asteroids and you could probably destroy Earth a lot more easily simply by grabbing some handy largish asteroids and sending them on their merry way towards Earth at some modest speed that's easily imparted with your spaceship.



    Conclusion :



    No need at all to mess around with ultra-relativistic micro-black holes when the universe provides you with much simpler and easy to handle "ammunition" in the form of basic asteroids.






    share|improve this answer









    $endgroup$












    • $begingroup$
      I was wondering about that speed, thanks for working it out.
      $endgroup$
      – Kevin
      9 hours ago










    • $begingroup$
      Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
      $endgroup$
      – Mark
      7 hours ago










    • $begingroup$
      Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
      $endgroup$
      – Gryphon
      4 hours ago










    • $begingroup$
      👍for addressing my comment too
      $endgroup$
      – user6760
      3 hours ago













    9












    9








    9





    $begingroup$

    The electromagnetic force from one electron on another and the gravitational force of this micro-black hole both follow an inverse square law. A grape about 1.5 cm in radius would have a mass of about 0.015 kg.



    When does the gravitational force of the grape exceed the electromagnetic force between electrons ? It's when :



    $$frac r R < sqrtfrac 4pi epsilon_0Gm_em_he^2 = 6.3times 10^-8$$



    Meaning the black hole would have to pass less than one ten millionth of the distance between electrons to have a significant influence on one. Away from than range the electron will happily go about it's business hardly disturbed at all.



    Even if a black hole passes this close the effect is only temporary. You're still nowhere near the event horizon of that black hole and so the electron will, at worst, be pulled away from it's normal motion and after some brief period when the black hole moves away it will simply recombined in some way with the bulk of atoms around it. It might cause a minute amount of damage on a molecular level (even allowing for millions of these micro black holes), but the net effect would be tiny, probably less that someone hitting a wall with their hand.




    How about they expell at fraction of c so we take length contraction into question?




    You seem to mean that to avoid Hawking radiation evaporation destroying these black holes before they even reach the black hole, they could be ejected at a high fraction of the speed of light.



    So how high a speed is needed to avoid them evaporating before they travel 100 meters, assuming your aliens like low level flying ?



    The fraction of the speed of light needed is :



    $$frac v c > frac 1 sqrt 1 + left( frac Tc L right)^2 $$



    Where $L$ is the distance they must travel and $T$ is the lifetime of the micro black hole before it evaporates.



    This works out at $frac v c approx 1 - 2times 10^-19$. That's insanely close to the speed of light.



    A million grapes of mass 0.015 kg will have a mass of 15,000 kg. But the energy required to get them moving at this insane fraction of the speed of light would be enormous. It equates to a mass about $2times 10^9$ times 15,000 kg. Or to put it another way, the ship firing these micro black holes would need to have a mass-energy of about $3times 10^13$ kg. The asteroid Vesta is substantially larger than this.



    So this is actually a small mass in terms of asteroids and you could probably destroy Earth a lot more easily simply by grabbing some handy largish asteroids and sending them on their merry way towards Earth at some modest speed that's easily imparted with your spaceship.



    Conclusion :



    No need at all to mess around with ultra-relativistic micro-black holes when the universe provides you with much simpler and easy to handle "ammunition" in the form of basic asteroids.






    share|improve this answer









    $endgroup$



    The electromagnetic force from one electron on another and the gravitational force of this micro-black hole both follow an inverse square law. A grape about 1.5 cm in radius would have a mass of about 0.015 kg.



    When does the gravitational force of the grape exceed the electromagnetic force between electrons ? It's when :



    $$frac r R < sqrtfrac 4pi epsilon_0Gm_em_he^2 = 6.3times 10^-8$$



    Meaning the black hole would have to pass less than one ten millionth of the distance between electrons to have a significant influence on one. Away from than range the electron will happily go about it's business hardly disturbed at all.



    Even if a black hole passes this close the effect is only temporary. You're still nowhere near the event horizon of that black hole and so the electron will, at worst, be pulled away from it's normal motion and after some brief period when the black hole moves away it will simply recombined in some way with the bulk of atoms around it. It might cause a minute amount of damage on a molecular level (even allowing for millions of these micro black holes), but the net effect would be tiny, probably less that someone hitting a wall with their hand.




    How about they expell at fraction of c so we take length contraction into question?




    You seem to mean that to avoid Hawking radiation evaporation destroying these black holes before they even reach the black hole, they could be ejected at a high fraction of the speed of light.



    So how high a speed is needed to avoid them evaporating before they travel 100 meters, assuming your aliens like low level flying ?



    The fraction of the speed of light needed is :



    $$frac v c > frac 1 sqrt 1 + left( frac Tc L right)^2 $$



    Where $L$ is the distance they must travel and $T$ is the lifetime of the micro black hole before it evaporates.



    This works out at $frac v c approx 1 - 2times 10^-19$. That's insanely close to the speed of light.



    A million grapes of mass 0.015 kg will have a mass of 15,000 kg. But the energy required to get them moving at this insane fraction of the speed of light would be enormous. It equates to a mass about $2times 10^9$ times 15,000 kg. Or to put it another way, the ship firing these micro black holes would need to have a mass-energy of about $3times 10^13$ kg. The asteroid Vesta is substantially larger than this.



    So this is actually a small mass in terms of asteroids and you could probably destroy Earth a lot more easily simply by grabbing some handy largish asteroids and sending them on their merry way towards Earth at some modest speed that's easily imparted with your spaceship.



    Conclusion :



    No need at all to mess around with ultra-relativistic micro-black holes when the universe provides you with much simpler and easy to handle "ammunition" in the form of basic asteroids.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 15 hours ago









    StephenGStephenG

    14.1k72051




    14.1k72051











    • $begingroup$
      I was wondering about that speed, thanks for working it out.
      $endgroup$
      – Kevin
      9 hours ago










    • $begingroup$
      Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
      $endgroup$
      – Mark
      7 hours ago










    • $begingroup$
      Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
      $endgroup$
      – Gryphon
      4 hours ago










    • $begingroup$
      👍for addressing my comment too
      $endgroup$
      – user6760
      3 hours ago
















    • $begingroup$
      I was wondering about that speed, thanks for working it out.
      $endgroup$
      – Kevin
      9 hours ago










    • $begingroup$
      Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
      $endgroup$
      – Mark
      7 hours ago










    • $begingroup$
      Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
      $endgroup$
      – Gryphon
      4 hours ago










    • $begingroup$
      👍for addressing my comment too
      $endgroup$
      – user6760
      3 hours ago















    $begingroup$
    I was wondering about that speed, thanks for working it out.
    $endgroup$
    – Kevin
    9 hours ago




    $begingroup$
    I was wondering about that speed, thanks for working it out.
    $endgroup$
    – Kevin
    9 hours ago












    $begingroup$
    Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
    $endgroup$
    – Mark
    7 hours ago




    $begingroup$
    Ultra-relativistic black holes would be considerably less effective than throwing Vesta at the Earth: as you note, they'll mostly just pass through Earth without doing anything.
    $endgroup$
    – Mark
    7 hours ago












    $begingroup$
    Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
    $endgroup$
    – Gryphon
    4 hours ago




    $begingroup$
    Interestingly, an actual grape going at that speed would be far more devastating than a grape-massed black hole. I don't have the time to do the math at the moment, but I'd guess it'd be enough to overcome the gravitational binding energy of the Earth.
    $endgroup$
    – Gryphon
    4 hours ago












    $begingroup$
    👍for addressing my comment too
    $endgroup$
    – user6760
    3 hours ago




    $begingroup$
    👍for addressing my comment too
    $endgroup$
    – user6760
    3 hours ago











    0












    $begingroup$

    If we take "size of a grape" to mean a gram, then a million of them would be 1 metric ton. When they evaporate, they release energy on the order of magnitude of a nuclear bomb. So New York would be devastated, but the earth as whole would not have large effects, although it might produce radioactive elements that would increase cancer rates.






    share|improve this answer









    $endgroup$

















      0












      $begingroup$

      If we take "size of a grape" to mean a gram, then a million of them would be 1 metric ton. When they evaporate, they release energy on the order of magnitude of a nuclear bomb. So New York would be devastated, but the earth as whole would not have large effects, although it might produce radioactive elements that would increase cancer rates.






      share|improve this answer









      $endgroup$















        0












        0








        0





        $begingroup$

        If we take "size of a grape" to mean a gram, then a million of them would be 1 metric ton. When they evaporate, they release energy on the order of magnitude of a nuclear bomb. So New York would be devastated, but the earth as whole would not have large effects, although it might produce radioactive elements that would increase cancer rates.






        share|improve this answer









        $endgroup$



        If we take "size of a grape" to mean a gram, then a million of them would be 1 metric ton. When they evaporate, they release energy on the order of magnitude of a nuclear bomb. So New York would be devastated, but the earth as whole would not have large effects, although it might produce radioactive elements that would increase cancer rates.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 1 hour ago









        AcccumulationAcccumulation

        61517




        61517



























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